Placing a C level rule below an N level rule interferes with the N level rules below that C level rule and can lead to data loss.

This is in spite of the fact that the parameter AllowSeparateNandCRules is set to T.

As an example if there is an element called Volume and the following rule is set it will cause the cells in the cube to have a status of not editable and can also lead to the loss of previously INPUT values:
['Volume']=N:IF(['Value']=0,0,CONTINUE);
['Volume']=C:0;
['Volume']=N:STET;

The STET command was added to prove the point that even if STET'ed, the C: rule overwrites - normally it would suffice to have the N Rule, continue, no other N Rules and cells would remain editable.

Cells in the cube viewer appear white and editable but their status in not editable. Trying to change their value results in a "data spread failed".

Changing the C: level rule to something other than zero shows that value at a C level but N levels are still affected.
Placing the C: level rule seems to work but who can say under what circumstances it won't.

This is definitely a bug and the attached model works as expected under 9.4, 9.5.2 and has been logged accordingly. Please be aware of the possible impact on your client's systems.

TM1 Version 10.2.2 - Windows, IBM SR42600689864

@MODS - please move this to the Bugs sub-forum as I do not have permissions to do so.

I can confirm that this is a definite bug in 10.2. I have come up against it in a few projects already. It can be worked around but only by rewriting rules by changing priority and putting in additional conditional tests. Needs to be fixed.

Please place all requests for help in a public thread. I will not answer PMs requesting assistance.

Just applied FP1 patch to test this issue - happy to report that TM1 behaves as it used to do.
I created a very simplistic example cube with Year, Month and Measures - Measures had Volume, Value, Extended to illustrate the issue.